This section provides background information related to the present disclosure, which is not necessarily prior art.
As a result of environmental and other concerns, plastic containers (more specifically polyester containers, such as polyethylene terephthalate (PET) containers for example) are now being used more than ever to package various commodities previously supplied in glass containers. Manufacturers and fillers, as well as consumers, have recognized that PET containers are lightweight, inexpensive, recyclable, and manufacturable in large quantities.
Blow-molded plastic containers have become commonplace in packaging numerous commodities. PET is a crystallizable polymer, meaning that it is available in an amorphous form or a semi-crystalline form. The ability of a PET container to maintain its material integrity relates to the percentage of the PET container in crystalline form, also known as the “crystallinity” of the PET container. The following equation defines the percentage of crystallinity as a volume fraction:
      %    ⁢                  ⁢    Crystallinity    =            (                        ρ          -                      ρ            a                                                ρ            C                    -                      ρ            a                              )        ×    100  where ρ is the density of the PET material, ρa is the density of pure amorphous PET material (1.333 g/cc), and ρc is the density of pure crystalline material (1.455 g/cc). Once a container has been blown, a commodity may be filled into the container.
Various food products such as salsa, fruit and vegetable juices, nectars, etc. are often stored in glass containers, or in polymeric containers with a metal or polymeric closure, in order to increase their shelf life. To reduce costs and enhance the seal of the closure, for example, a cold-fill, hot-fill or hot-fillable PET, warm-fill, or retort container suitable for pasteurization in the range of 50° F.-250° F. that can couple with a metal closure would be desirable.